The present invention relates, in general, to a disc-type brake system and, more particularly, the invention is directed to an improved brake jaw bearing arrangement in a disc-type brake brake lever for vehicular and/or industrial-type uses.
Disc brake systems have been known for the last several years. They are in wide use on most of the over-the-road type vehicles, many of the rail vehicles, and in a number of industrial applications. Even so, disc brakes are still a relatively infant technology. Furthermore, in relation to the automotive industry, even if the disc brakes are listed as standard equipment by the manufacturer of the vehicle, it is a technology for which the consumer must pay an added premium; such premium is in the form of a higher base sticker price. Some, but not all, of the major factors associated with the added cost for this improved-type of braking system will be discussed below. One such factor of importance is the care that must be taken to assure, as far as possible, that the bearing arrangement for the disc brake jaw precludes dirt or other extraneous foreign substances from penetrating into the bearings; such bearings reducing the frictional resistance as the brake levers move relative to one another. When, for example, dirt or other extraneous matter does penetrate into the bearing arrangement, excessive wear can and often does occur. This necessitates costly repairs for the vehicle owner, or industrial user, which involves the use of both skilled labor and new parts.
It is of importance not only to the automotive and railroad industry, but to the consuming public as well, to achieve a design for a bearing arrangement for both brake levers of a disc brake arrangement that is as free of wear as possible or practical within reasonable price constraints. Because of this importance, consideration has been given to providing a disc-type brake system having a bearing arrangement incorporated therein which utilizes an increased number of seals. The additional seals provided would be a number which, in the manufacturer's opinion, would be sufficient to prevent the undesirable penetration of extraneous substances into the bearings. The additional seals, however, require an additional expenditure by the disc brake manufacturer, which the consumer must ultimately absorb. Therefore, the added cost must be balanced against the longer life expectancy for the component parts and the resulting lower maintenance costs. There would still remain, however, even with this added precaution and lower cost, a certain degree of uncertainty that such increased number of seals would continue to be operative over an extended period of operation of the braking system when installed on a vehicle or industrial application.
An additional disadvantage of the prior art type brake jaw bearing arrangements for the brake levers of vehicular-type disc brakes that is recognized in the industry is the significant number of component parts required. One very obvious disadvantage to having a larger number of components is the fact that they will wear out; and as wear occurs, the efficiency of the system may be impaired until finally they will have to be replaced at a significant cost, in many cases to the vehicular owner or industrial user of the system. What has not been obvious heretofore is a disc brake system having fewer components.
Another obvious disadvantage is the added skilled labor and material costs incurred by the vehicle manufacturer or industrial user of a disc brake system for the purchase and assembling of these extra parts.
In addition, and possibly even the single biggest disadvantage in prior art disc brakes having a large number of parts, is the maintenance of the system. This may be a particular problem in the automotive area unless the mechanic entrusted with the repair and/or maintenance of one of the most critical parts of a vehicle is skillful and, even more importantly, is concerned about the quality of his or her workmanship.
Prior art brake jaw bearing arrangements for the brake levers on disc-type brake systems have yet another extremely serious drawback, which contributes to the considerable amount of wear to the component parts. This drawback is the number of parts which must move relative to each other. Obviously, relative movement between such parts adds to the wear and tear of the component parts, and the wear and tear adds to the maintenance costs that must be absorbed by the owner of the vehicle or machinery having such disc brakes.
As with the obvious problem with the seals discussed above, even though it is well known in the industry that parts which move relative to one another cause wear, the solution to reducing the number of such parts has not been heretofore obvious.
One other disadvantage with prior art disc brakes is the care which must be taken to ensure surface contact of the entire pad with the disc brake member, such as a rotor, or the like.
Many of the above disadvantages relate primarily to automotive disc brakes, while others are found primarily when disc brakes are used in the railroad industry or industrial application. However, because of their improved performance, they are being used on a wider scale. This is particularly true in the rapid transit area of the railroad industry. See, for example, British Pat. No. 1,527,135 incorporated herein by reference. Also, of interest is U.S. Pat. No. 3,986,584 also incorporated herein by reference.
Therefore, notwithstanding all of the above enumerated disadvantages to prior art disc brakes, it is recognized that they have made a substantial impact on vehicle safety and comfort, therefore disc brakes are of extreme importance in vehicle use.